hello all im surprised that no one mentioned that the spark plugs in the magnito engines is a resistor type, and should never be replaced with a non resistor. Usually the number on the plug will have an ( r) in it. This also applies to the c&h type ignitions. In the past I have had ni-cad battery packs cause interference in the radio when the engine was running. These were on both ignition and reciever packs. Had one pack that would run the ignition ok, but when hooked up to the radio system, would not work at all, dead. Go figure. Just make sure you have new or well maintained ni-cad paks in your equipment. Hope this helps Jack